In order to satisfy the requirements of a high data rate, a carrier aggregation technology has been proposed in a long-term evolution-advanced (LTE-A) system, so as to be able to provide bandwidth values required by the high data rate. In the carrier aggregation technology, each aggregated carrier is referred to as a component carrier (CC).
In Rel-10 of an LTE-A system, the types of carriers comprise backward compatible carriers and non-backward compatible carriers. The backward compatible carriers may be accessed by a terminal in Rel-10, and may be accessed by terminals in Rel-8 and Rel-9. While the non-backward compatible carriers may be accessed by a terminal in Rel-10 after configuration, and cannot be accessed by terminals in Rel-8 and Rel-9. Wherein, the non-backward compatible carriers comprise extension carriers and carrier segments. Such two types of carriers cannot operate independently, and need the backward compatible carriers to coordinate in operation. The backward compatible carriers are hereinafter referred to as stand-alone carriers.
In an LTE system, three methods for downlink resource assignment are defined, that is, resource assignment type 0, resource assignment type 1 and resource assignment type 2 (refer to 3GPP TS36.213 v9.3.0).
In resource assignment type 0, a resource block group (RBG) consists of several consecutive resource blocks (RBs). In assigning resources by a base station for a terminal, an RBG is taken as a minimum assignment unit, that is, it decides whether to assign a certain RBG to the terminal. Wherein, the RGB size is determined according to the system bandwidth. After obtaining a resource assignment result, the base station will notify the terminal of the result via a resource assignment (RA) domain in a downlink resource assignment indicator (DCI).
However, in the implementation of the present invention, the inventors found that there exist a terminal of Rel-8/9/10 and a terminal of Rel-11 under the coverage of a base station at the same time. In a case where the base station is configured with a stand-alone carrier and a carrier segment at the same time, the stand-alone carrier allows terminals of all types to be accessed, while the carrier segment can only be configured for a terminal of Rel-11, and is after the terminal of Rel-11 accesses to a stand-alone carrier. Hence, a case will occur where the system bandwidths of the terminal of Rel-8/9/10 and the terminal of Rel-11 are different.
For example, the base station has a spectrum of a bandwidth of 32 RBs, among which the bandwidth of a stand-alone carrier is 25 RBs, and 6 RBs may be used as carrier segments. All the terminals may access to a stand-alone carrier of a system bandwidth of 25 RBs. After a terminal of Rel-11 accesses to the stand-alone carrier, the base station may configure the terminal with carriers segments of 6 RBs after the base station learns that the version of the terminal is Rel-11. In this way, the system bandwidth of the terminal of Rel-11 is 31 RBs, while the system bandwidth of the terminal of Rel-8/9/10 is 25 RBs. In assigning resources by using resource assignment type 0, the sizes of the RBGs to which the terminal of Rel-8/9/10 and the terminal of Rel-11 correspond are different. If the resource assignment is performed according to respective RBGs, the utilization of the RBs will be lowered on the premise of not limiting the scheduling algorithm of the base station, resulting in the problem of waste of resources. There is no effective way of solving such a problem at present.
It should be noted that the above description of the background art is merely provided for clear and complete explanation of the present invention and for easy understanding by those skilled in the art. And it should not be understood that the above technical solution is known to those skilled in the art as it is described in the background art of the present invention.